Before the 1800s, the Pawnee mostly used flint tools. Less sharp, but holds an edge better than obsidian. idk if they cut the leather for that map with flint or with a metal blade they traded in, but it seems kinda pointless when the objection is coming from a guy who, unlike pre-Colombian Pawnee, would be miserably trampled to death if he had to hunt bison with flint arrows and without a horse.